Epoxy Emulsion Research Articles

Effect of Epoxy Binder on Fire Protection and Bonding Strength of Intumescent Fire Protective Coatings for Steel

This study focuses on the effect of epoxy emulsion, a binder for producing water-borne intumescent fire protective coating for steel structures. The influence of binder on the fire resistive performance, char formation, thermal stability and bonding strength of the coatings were investigated in detail by using Bunsen burner test, thermogravimetry analysis (TGA), field emission scanning electron microscopy (FESEM) and Instron microtester. It was found that the fire protection performance and foam structure of coating sample D2 was significantly improved by adding 10wt% of epoxy resin which produced the greatest thickness of char layer. In addition, TGA results showed that the residue weight of coating D2 was higher than coating sample D3 with 15wt% of epoxy. This indicated that sample D2 has better anti-oxidation and thermal stability. The results of Instron microtester indicated that the bonding strength of the coatings was improved with the increase of epoxy content.

The Mechanisms of Epoxy Latex Coatings Curing at Ambient Temperature Comparison with Solvent-Type Ones

The performance and behavior of epoxy latex coatings are different from solvent-type ones.It is decided by the distinct curing mechanism. The solvent-type epoxy film obtained from epoxy resin and curing agent by homogeneous reaction, namely, the state of epoxy resin and curing agent is uniform. However, epoxy latex film made from epoxy resin emulsion or dispersion and water soluble amine by polyphase reaction. So the determination of potlife of epoxy latex can be showed by film gloss changes with residence time, dissimilar with solvent-type by the index of viscosity. The modern infrared spectrum measure shows that the epoxy groups in the dried epoxy latex film exist even if EEW to HAV proportion is 1.2:1. This also testifies the incomplete polyphase reaction mechanism of epoxy emulsion coating curing at ambient temperature.

Polyaniline/Epoxy Composite Emulsion Coatings for Anticorrosion to Mild Steel

Doped water-dispersible polyaniline (PANI) emulsion were synthesized by emulsion polymerization in aqueous medium and characterized by dc conductivity and Transmission electron microscope (TEM). The results showed the PANI has bar-like shape and the diameter is about 200nm. The composite anticorrosion coatings of PANI emulsion and waterborne epoxy resin emulsion (EP) were prepared by mixture in aqueous medium and used for corrosion protection of mild steel. Open circuit potential (OCP) and Electrochemical impedance spectroscopy (EIS) demonstrated that the PANI/EP composite coatings have better anticorrosion properties than EP. It’s impedance and corrosion potential is higher. Scanning electron microscope (SEM) and Energy dispersive spectrometer (EDS) showed that the oxidation film formed on the metal surface and prevent corrosion effectively. The anticorrosion coatings are environmental friendly because of water dispersion medium.

Influences of binder on fire protection and anticorrosion properties of intumescent fire resistive coating for steel structure

The combination of epoxy emulsion and self-crosslinked silicone acrylate (SSA) emulsion was used as mixed binder for preparing water-borne intumescent fire resistive coating. The influences of binders on the properties and char formation of the coatings were investigated in detail by using thermogravimetry (TG), scanning electron microscope (SEM), X-ray diffraction (XRD), X-ray fluorescence spectrometry (XRF), rheological measurement, fire protection test and anticorrosion property test. It was found that the fire protection and foam structure of the coating was significantly improved by adding 14% SSA (by mass). The TG results showed that adding SSA increased the residue weights of the coatings. The XRF results demonstrated that anti-oxidation of the coatings was improved by adding SSA into the mixed binders. The results of anticorrosion property test indicated that the anticorrosion property of the coatings was enhanced with increase of content of SSA.

Preparation and properties of a new composite of epoxy emulsion (EEM) modified cement

High performance cement based composite materials was prepared by adding epoxy emulsion. The epoxy emulsion was synthesized with epoxy phosphoric acid ester and poly-glycol in laboratory. This epoxy emulsion has advantages over other emulsion, such as dehydrated slightly, and, well film formation abilities. The mechanical properties corruptness resistance and structure of epoxy emulsion modified cement mortars were studied. Experimental results show that the mechanical properties of modified cement mortars are slightly increased with increasing epoxy emulsion content, especially the flexure strength. The corruptness resistance of all modified mortars is better than the unmodified mortar. The polymer film forms the bridge phases between the matrix and the aggregate regions, and forms a three-dimension structure in the cement hydration system, which improves the mechanical properties of modified mortars.

Water-Based Polyaniline/Montmorillonite/Epoxy Composite Coatings for the Corrosion Protection of Mild Steel

Polystyrene sulfonic acid (PSSA) doped water-dispersible polyaniline (PANI) /montmorillonite (MMT) clay composites were firstly synthesized by intercalation polymerisation in aqueous medium and characterized by XRD and FT-IR. The results showed exfoliated silicate nanolayers of MMT clay dispersed in the PANI matrix and has interaction involving hydrogen bonding between the PSSA-PANI chain and the surface of the MMT clay layer. This composites is more thermal stable than that of without clay samples and results in good stable temperature-dependent dc conductivity [σdc(T)] as temperature changed. The composite anticorrosion coatings of PANI/MMT and waterborne epoxy resin emulsion (EP) were prepared by mixture in aqueous medium and used for corrosion protection of mild steel. Open circuit potential (OCP), Electrochemical impedance spectroscopy (EIS) and Tafel plot demonstrated that the PANI/MMT/EP composite coatings have better anticorrosion properties than PANI/EP, MMT/EP and PANI/MMT/EP mixture. It’s impedance and corrosion potential is higher and the corrosion current density is lower. The anticorrosion coatings are environmental friendly because of water dispersion medium. Introduction

Waterborne epoxy resin modified by AMPS

A stable epoxy emulsion was prepared with epoxy resin (EP) as raw material, 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) as modifier and benzoyl peroxide as initiator. By criterion of yield of the copolymer AMPS-EP, water-solubility, change of the acid value and intrinsic viscosity [η] along with reaction time, the copolymerization course was deduced. It is found that during the process, AMPS takes part in both the grafting copolymerization with epoxy principal chain and the ring-opening polyaddition with epoxy group. It is also discovered that the yield of AMPS-EP and water dispersing varies with reaction time. When it reaches 1.5 h, AMPS-EP can obtain good water-solubility; but the water-solubility will go bad gradually if it exceeds 3.5 h. IR spectrum analysis indicates that partial epoxy group partially remains and the others create sulfonic ester.

A novel method for preparing epoxy-containing microcapsules via UV irradiation-induced interfacial copolymerization in emulsions

A novel method for producing epoxy resin-containing microcapsules via UV-initiated radical copolymerization in an epoxy emulsion was developed. Epoxydiacrylates and a polymerizable emulsifier were employed as the wall-formers, which tended to accumulate at the exterior layer of epoxy colloids during the emulsification process. Upon exposure to UV light, the shell phase consisting of the wall-formers was rapidly cured into solid to generate microcapsules with epoxy as the core substance. In this paper, the characteristics of the resultant microcapsules, including size and size distribution, chemical features, surface morphology, thermal stability, core content, and reactivity with curing agent, were studied. Also, the factors influencing the preparation of microcapsules were analyzed. Moreover, the optimum synthetic conditions of UV irradiation to prepare the microcapsules were determined by orthographic factorial design. Compared to the conventional thermal initiation, the present UV-aided encapsulation saves time.

Effects of emulsion sizing with nano-SiO2 on interfacial properties of carbon fibers/epoxy composites

Nano-SiO2 particles were used to modify epoxy emulsion sizing of carbon fibers to improve the interfacial properties of carbon fibers reinforced epoxy composites. The mechanical interfacial strength between fibers and matrix was investigated by the single fiber fragmentation test and the 3-point short beam shear test, respectively. Dynamic contact angle analysis (DCAA), X-ray photoelectron spectrometry (XPS) and atomic force microscopy (AFM) were performed on the carbon fibers with unmodified sizing and nano-SiO2 modified sizing. The results indicated that modified sizing with nano-SiO2 slightly increased the surface energy, the hydroxyl functional group and the surface roughness of carbon fibers compared to unmodified sizing, so that the interfacial shear strength (IFSS) of the single fiber composites and the interlaminar shear strength (ILSS) of composites were enhanced. SEM images of fracture sections of composites proved powerfully that the interfacial adhesion between fibers and matrix was improved after nano-SiO2 modified emulsion sizing treatment.

Effect of nano-SiO 2 modified emulsion sizing on the interfacial adhesion of carbon fibers reinforced composites

The influence of nano-SiO 2 modified epoxy emulsion sizing on the interfacial adhesion properties of carbon fibers reinforced composites was investigated. The interfacial interaction between carbon fibers and the matrix was characterized by X-ray photoelectron spectrometry (XPS), scanning electron microscopy (SEM) and three-point short-beam shear testing. The results showed that the amount of hydroxyl groups was slightly increased on the carbon fibers surface after treatment with nano-SiO 2 modified sizing. Compared to the unsized composites, the interlaminar shear strength (ILSS) values for the composites with unmodified sizing and nano-SiO 2 modified sizing were increased by 9% and 14%, respectively. The holes and carbon fibers pullout were not observed in their fracture sections. Surprisingly, the fracture section of the composites with nano-SiO 2 modified sizing was more compact and the fiber debonding was more difficult.

Properties of polymer-modified mortars using epoxy and acrylic emulsions

Water based polymer systems are often used for improvement in the properties of plain cement mortar or concrete. Presently, latexes of a single or combinations of polymers like polyvinyl acetate, copolymers of vinyl acetate–ethylene, styrene–butadiene, styrene–acrylic, and acrylic and styrene butadiene rubber emulsions are generally used. One of the limitations of these polymer systems is that they may re-emulsify in humid alkaline conditions. To overcome this problem, an epoxy emulsion based polymer system has been developed. In this paper the properties of the cement mortar modified with this newly developed epoxy emulsion are compared with those of the acrylic-modified mortar. The results showed that the mortars with the newly developed system have superior strength properties and better resistance to the penetration of chloride ions and carbon dioxide.

Cationic polymerization of emulsified epoxy resins

Whereas free-radical emulsion polymerization has been studied extensively, published reports of cationic (i.e., acid catalyzed) polymerizations of emulsified monomers of any type are rare, and we have found no reported examples of non-reversible emulsion polymerizations catalyzed by Brønsted acids. We recently discovered that treatment of an emulsion of liquid epoxy resin with select superacid catalysts yields polymeric polyols. Catalysis with 1% perchloric acid at room temperature yields a product with a number average molecular weight of 1650, and a polydispersity of 5.0 as measured by gel permeation chromatogram. The polyol’s structure differs from that of conventional high molecular weight epoxy resins prepared by the advancement process in several ways, including the incorporation of two glycidyl units in the repeat unit. The molecular weight of the product depends on the superacid catalyst employed. The product was shown to be much lower in levels of residual bisphenol-A diglycidyl ether (BADGE) and bisphenol-A than conventional epoxy resins, which is an issue of significant importance to producers of can linings for foods and beverages. Polyols prepared by this process were cross-linked with melamine–formaldehyde resins to produce water-borne coatings free of added cosolvent that develop excellent solvent resistance at lower bake temperatures than traditional epoxy resins.

New polymeric polyol for thermoset coatings: Superacid-catalyzed copolymerization of water and epoxy resins

Though free-radical emulsion polymerization has been studied extensively, published reports of cationic (i.e., acid-catalyzed) polymerizations of emulsified monomers are rare. It was recently discovered that treatment of an emulsion of liquid epoxy resin with select superacid catalysts yields a polymeric polyol. Catalysis with one percent perchloric acid at room temperature yields a product with a number average molecular weight of 1650, and a polydispersity of 5.0 as measured by GPC. The polyol’s structure differs from that of conventional high molecular weight epoxy resins prepared by the advancement process in several ways, including the incorporation of two glycidyl units in the repeat unit. In essence, the product is a copolymer of the epoxy resin and water, in which water is incorporated in the repeat unit structure by reaction with two epoxide groups. A similar product can be prepared by solution polymerization, where the molecular weight is controlled by the ratio of water to epoxy resin. The product was shown to have lower levels of residual bisphenol-A diglycidyl ether (BADGE) and bisphenol-A than conventional advanced epoxy resins. Polyols prepared by these new processes were crosslinked with melamine-formaldehyde resins in waterborne coating formulations which were free of added cosolvent, as well as solventborne coating formulations. The coatings developed excellent solvent resistance at lower bake temperatures than traditional epoxy resins.

The Effect of a Silane Coupling Agent on the Hydrolytic Durability of Thin Epoxy Resin Films

A coating consisting of an aqueous emulsion of epoxy resin and a polyamidoamine hardener has been developed which effectively strengthens glass containing large flaws. By substituting a silane coupling agent for some of the resin the deleterious effects of ageing can be prevented; the strength of samples aged for two months at 52°C and 96% relative humidity was not reduced, maintaining a 197% improvement in strength with respect to uncoated samples. X-ray photoelectron spectroscopy showed that the accelerated ageing treatment led to an increase in the concentration of hydroxyl groups in the resin resulting from the scission of amine crosslinking groups. The migration of sodium from the substrate to the surface was also demonstrated. It is concluded that the coupling agent does not render the coating immune to hydrolytic ageing or protect the substrate from hydrolytic attack. It only provides a hydrolytically-stable linkage between the two.

Epoxy Resin Particles, 3. Particle Formation of Epoxy Resin in Aqueous Emulsion State

A Bisphenol A-type epoxy resin is readily emulsified in aqueous medium with an ethylene oxide adduct to a Friedel-Crafts reaction product of styrene and 4-(4-cumyl)phenol as emulsifier. The resultant epoxy resin emulsion is reacted with amine-type hardeners to obtain epoxy resin particles that are fully cross-linked. The size and size distribution of the resultant particles are almost comparable to those of the primarily formed emulsion particles which are determined by the amount of emulsifier, mixing temperature and speed. The average diameter of the finally obtained particles ranges from 0.5 to 22 μm depending on the reaction conditions. The particles hardened with 1,2-diaminoethane (DEA) have a spherical form with homogeneous surface, whereas the particles hardened with N,N ′-bis(2-aminoethyl)-1,2-diaminoethane (TTA) have a shrunk appearance with rough surface. These particles can readily be isolated from the dispersion without causing the solvent-derived pollution for environment.

Epoxy Resin Particles, 3. Particle Formation of Epoxy Resin in Aqueous Emulsion State

A Bisphenol A-type epoxy resin is readily emulsified in aqueous medium with an ethylene oxide adduct to a Friedel-Crafts reaction product of styrene and 4-(4-cumyl)phenol as emulsifier. The resultant epoxy resin emulsion is reacted with amine-type hardeners to obtain epoxy resin particles that are fully cross-linked. The size and size distribution of the resultant particles are almost comparable to those of the primarily formed emulsion particles which are determined by the amount of emulsifier, mixing temperature and speed. The average diameter of the finally obtained particles ranges from 0.5 to 22 μm depending on the reaction conditions. The particles hardened with 1,2-diaminoethane (DEA) have a spherical form with homogeneous surface, whereas the particles hardened with N,N ′-bis(2-aminoethyl)-1,2-diaminoethane (TTA) have a shrunk appearance with rough surface. These particles can readily be isolated from the dispersion without causing the solvent-derived pollution for environment.

New waterborne epoxy coatings based on cellulose nanofillers

New nanocomposites based on a waterborne epoxy emulsion and a suspension of cellulose crystallites were prepared by film casting in order to obtain coatings displaying both flexibility and stiffness. Tunicin cellulose whiskers are attractive reinforcing fillers due to their high aspect ratio, large interface area, and, significant mechanical properties). Typical processing problems for this type of composite are related to high viscosity values of filled polymers in the in the molten state, the incompatibility between hydrophobic matrices and hydrophilic cellulose and the formation of hydrogen bonds between cellulose of this type of natural fibres in an epoxy matrix. The aim of this work is to solve some of the problems above mentioned by selecting the nature of the components used for coating synthesis film processing. The dynamic mechanical properties display an important improvement of the composite modulus in the rubbery state of the matrix at low concentrations of fillers, which can not be expected other cellulose based fibers.

An epoxy novolac emulsion system for ambient cure protective coatings

Water-borne two-pack coatings based on a novel low particle size epoxy novolac emulsion, crosslinked with polycycloaliphatic polyamine provide a good balance of several properties. Because the films cured possess a high crosslink density of cross linkage, expectations such as rapid through film drying time, high hardness development at an early stage during cure, very good film formation at 10°C and 80% R.H., and chemical resistance can be met. However, there are also adverse aspects to consider regarding the combination of a water-insoluble hydrophobic polyamine and a modified epoxy novolac emulsion. eg no visible end of pot life, relative short pot life and a brittleness of coatings associated with a tendency to peeling when exposed to salt spray and humid conditions. The study also revealed that the quality of a cured two-component epoxy binder emulsion system depends to a great extent on the quality of the emulsion, particularly on the size and distribution of the droplets. A low particle size epoxy emulsion improves the film formation, drying time, water resistance, gloss, adhesion and hardness. For this purpose epoxy emulsions with a narrow particle size distribution and relatively low particle size (mean value ca. 0.4 µm) can be developed using a proprietary mechanical emulsion process. The aqueous coating system described may be useful for applications where conventional epoxy novolacs are already used as low temperature heat cure coatings like drill pipe coatings, oil pipelines and fuel storage tanks and in fields where their chemical, water and solvent resistance can be utilised. Further ambient cure applications may be protective coatings for indoor use, eg food factories, schools, hospitals and office buildings, industrial maintenance coatings for concrete, mortar, bricks, plaster and wood.

Two-component aqueous epoxy binders free of volatile organic content (VOC)

Water-borne two-pack coatings based on a novel epoxy resin emulsion, cross-linked with three different amine group containing curing agents, are discussed. The aqueous binders developed at the Research Laboratory at Dow Deutschland Inc. are free of volatile organic content. The epoxy resin emulsion has a low MFFT (minimum film formation temperature) and is hence capable of forming a continuous film at low temperatures and good emulsifying properties. The interaction is discussed between the epoxy emulsion, pigments and hardeners which are in aqueous solution, emulsion or hydrophobic (non-aqueous) form. Some of the described systems will gain interest in a wide range of applications because of their excellent properties, including adhesion to various substrates, resistance to chemicals, solvents and water, hardness and toughness. The predicted major applications for such systems include concrete, plastic and wood coatings, and anti-corrosive systems for steel and other metals.

Convective and radiant (IR) curing of bulk and waterborne epoxy coatings as thin layers. Part I: Methodology

AbstractA method for studying the curing of 100 μm‐thick epoxy‐based layers coated on steel substrates is described. A simple waterborne epoxy reactive system based on a diglycidylether of bisphenol‐A prepolymer and with a polyether triamine was set up by emulsifying the epoxy resin with the use of an ethoxylated‐nonylphenol emulsifier. The parliculur phenomena involved during the isothermal curing of such an epoxy emulsion were decomposed by considering the same formulation without water and without water + emulsifier. The chemical kinetics were determined by DSC and by size exclusion chromatography. As previously proposed for numerous epoxy‐amine reactive systems, for the three types of coatings, a second‐order autocatalytic law was able to interpret the data. The presence of water delays the gelation characterized by rheological measurements. As a consequence, the epoxy conversion at the gel point increases. This phenomenon can be related to the inhomogeneous polymerization process during which the epoxy groups can be trapped into the initial epoxy particles. In addition, the microdielectrometry technique was used to follow the curing degree of the epoxy reactive system of thin layers during the drying and curing processes under radiant heatings such as infrared curing.